Calculus Examples

$\frac{2 (x^{2} - 9)}{x^{2} - 4}$

Step 1

Since $2$ is constant with respect to $x$ , the derivative of $\frac{2 (x^{2} - 9)}{x^{2} - 4}$ with respect to $x$ is $2 \frac{d}{d x} [\frac{x^{2} - 9}{x^{2} - 4}]$ .

$2 \frac{d}{d x} [\frac{x^{2} - 9}{x^{2} - 4}]$

Step 2

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = x^{2} - 9$ and $g (x) = x^{2} - 4$ .

$2 \frac{(x^{2} - 4) \frac{d}{d x} [x^{2} - 9] - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3

Differentiate.

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Step 3.1

By the Sum Rule, the derivative of $x^{2} - 9$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 9]$ .

$2 \frac{(x^{2} - 4) (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 9]) - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$2 \frac{(x^{2} - 4) (2 x + \frac{d}{d x} [- 9]) - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3.3

Since $- 9$ is constant with respect to $x$ , the derivative of $- 9$ with respect to $x$ is $0$ .

$2 \frac{(x^{2} - 4) (2 x + 0) - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3.4

Simplify the expression.

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Step 3.4.1

Add $2 x$ and $0$ .

$2 \frac{(x^{2} - 4) (2 x) - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3.4.2

Move $2$ to the left of $x^{2} - 4$ .

$2 \frac{2 \cdot (x^{2} - 4) x - (x^{2} - 9) \frac{d}{d x} [x^{2} - 4]}{{(x^{2} - 4)}^{2}}$

Step 3.5

By the Sum Rule, the derivative of $x^{2} - 4$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 4]$ .

$2 \frac{2 (x^{2} - 4) x - (x^{2} - 9) (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 4])}{{(x^{2} - 4)}^{2}}$

Step 3.6

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$2 \frac{2 (x^{2} - 4) x - (x^{2} - 9) (2 x + \frac{d}{d x} [- 4])}{{(x^{2} - 4)}^{2}}$

Step 3.7

Since $- 4$ is constant with respect to $x$ , the derivative of $- 4$ with respect to $x$ is $0$ .

$2 \frac{2 (x^{2} - 4) x - (x^{2} - 9) (2 x + 0)}{{(x^{2} - 4)}^{2}}$

Step 3.8

Combine fractions.

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Step 3.8.1

Add $2 x$ and $0$ .

$2 \frac{2 (x^{2} - 4) x - (x^{2} - 9) (2 x)}{{(x^{2} - 4)}^{2}}$

Step 3.8.2

Multiply $2$ by $- 1$ .

$2 \frac{2 (x^{2} - 4) x - 2 (x^{2} - 9) x}{{(x^{2} - 4)}^{2}}$

Step 3.8.3

Combine $2$ and $\frac{2 (x^{2} - 4) x - 2 (x^{2} - 9) x}{{(x^{2} - 4)}^{2}}$ .

$\frac{2 (2 (x^{2} - 4) x - 2 (x^{2} - 9) x)}{{(x^{2} - 4)}^{2}}$

Step 4

Simplify.

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Step 4.1